Electron discharge device



Aug. 29, 1939- P. SCHOONENBERG ELECTRON DISCHARGE DEVICE Filed Nov. 20, 1937 I NV EN TOR. NC'RAS swam/mama W 54;

A TTORN E Y.

Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE assignor to N. V. Phili ps Gloeilampenfabrieken,

Eindhoven, Netherlands Application November 20, 1937, Serial No. 175,595 In the Netherlands January 25, 1937 1 Claim.

The invention relates to electric tubes, more particularly to electron discharge devices of small dimensions.

Small sized envelopes of discharge tubes have 5 been made with a glass disc-shaped press or stem, carrying the current-supply conductors for the electrodes, sealed along its edge to the envelope. Unfortunately, heat applied at the edge of the glass press in joining it to the envelope, often .0 stresses the glass around the lead-in conductors and damages the glass-to-metal seals. This difficulty is usually encountered in the manufacture of discharge tubes with a large number of current-supply conductors in the press.

5 Good results have been obtained, according to this invention, by molding and pressing a cupshaped press of vitreous material, such as glass or ceramic, with a substantially flat bottom containing lead-in conductors and a cylindrical side wall or flange integral with and normal to the flat bottom portion of the cup. The rim of the press flange may be joined to the rim of a cylindrical bulb or shell of metal or glass. The envelope of the improved tube can be easily manufactured with molds and stamps so that its dimensions are only slightly larger than those of the electrode system. The molded-in currentsupply conductors may, if desired, be made sufficiently rigid to serve as contact pins for the 0 tube. An important advantage of discharge tubes made according to this invention is that the press and shell can easily be made with the same dimensions which is of importance in mounting the electrodes in the finished envelope. Envelopes 5 of uniform size and shape are particularly easy to make with molded glass parts.

According to one embodiment of the invention, an electric discharge tube is made of a molded shell of glass or a drawn shell of metal and a molded press, containing at least four currentsupply conductors, the rims of the press flange and the shell being slightly flared and sealed together.

The exhaust tube may be secured either to the i press or to the end of the shell opposite the press.

In some cases it may be desirable to coat a thin layer of glass on the current-supply conductors before they are molded into the press. The conductors may be of a material commonly used for lead-ins such as chrome-iron or dumet.

The invention is explained more fully with reference to the accompanying drawing in which Figure 1 represents in section an electric discharge tube manufactured in accordance with the invention, and Figure 2 is a view of the parts of the improved tube before assembly.

The envelope of the tube made in accordance with this invention comprises a cylindrical bulb or shell I, shown by way of example as a vitreous material such as glass, although the shell may,

if desired, be made of metal. The shell is closed at its upper end and encloses an electrode assem- 5 bly 2 with conventional transverse spacers at the ends of the assembly. The lower end of the shell is closed by a press 3, which according to this invention is cup-shaped with a substantially flat disc-shaped bottom portion 4 and a cylin- 1o drical side wall or flange 6 of molded insulating material, such as glass or ceramic. Conductors 5 sealed transversely through the bottom portion of the press may be arranged either in alignment or in a circle concentric with the periphery of the bottom. The cylindrical side or flange 6 of the press may conveniently be molded with a diameter equal to the diameter of the shell and may be provided along its rim with a slight outward flare l of the same size as the flare 8 on the rim of the shell.

After the cup-shaped press has been formed, with lead-in wires 5 molded gas tight in place, the electrode assembly 2 may conveniently be joined to the upper ends of the lead wires and inserted into the shell, bringing the flared rims 1 into registry with the flared rim 8. By applying flames to the contacting flared rims l and 8 they may be'softened and sealed gas tight to complete the envelope. The heated sealing area of the envelope is, according to this invention,

a substantial distance from the lead-in seals in the bottom of the press which, it has been found, minimizes fractures of the glass-to-metal seals at the lead-in wires. The tube may then be exhausted through exhaust tube 9 connected to the top of the shell as shown or to the press and sealed off in the usual manner.

I claim:

An envelope for an electron discharge device .40 comprising a cylindrical glass shell, a cup-shaped press for closing the end of said envelope comprising a thick vitreous disc integrally joined to a cylindrical side wall of a diameter equal to the diameter of said shell, said side wall and shell being relatively thin, the rims of the shell and the side wall being flared and sealed together in a gas-tight annular seal, and relatively heavy lead-in conductors extending through in said vitreous disc of the press, with the material of the disc molded around and sealed gas-tight directly to each conductor, the junction between the material and the conductor being extensive to provide a strong mechanical support for the exterior ends of the conductors.

PANCRAS SCHOONENBERG. 

